In the discussion of the state of the art that follows, reference is made to certain structures and/or methods. However, the following references should not be construed as an admission that these structures and/or methods constitute prior art. Applicant expressly reserves the right to demonstrate that such structures and/or methods do not qualify as prior art against the present invention.
Blister packages are used to package a variety of different products. Blister packages typically comprise two pieces which are referred to as a blister on one side (e.g., a plastic carton often having a formed cavity to receive a product) and a card on the other side (e.g., a panel of plastic, cardboard, or other suitable material and which is often planar). Depending on the item to be sealed and the desired function of the package, e.g., multiple items separately contained in one blister seal or a single item in a single blister seal, or multiple differently shaped containers in a single blister seal, the blister packages are differently shaped.
During sealing of a blister package, the contents to be sealed are placed between the two pieces, and heat is applied to the blister package in a particular pattern, thereby sealing the blister to the card, thus sealing the contents inside the blister package. It is often necessary to apply a temperature of at least 300 degrees Fahrenheit to the blister packages to achieve a proper seal, and temperatures are sometimes required up to around 550 degrees Fahrenheit. This can be accomplished with an electrical resistance heater that is shaped so that it contacts and transfers heat to the blister packages in a particular pattern. However, for every different shaped blister package, the heater must be differently shaped to apply the proper pattern of heat to the blister package.
One option would be to maintain a number of differently shaped heaters to seal the different shaped blisters and to change the heater depending on the blister to be sealed. However, heaters are relatively costly and relatively burdensome to replace, therefore, changing a heater to correspond to different shaped blisters presents a number of issues.
Another solution is to use differently shaped heat sealing members that removably connect to the heater. The different heat sealing members each posses the particular shape required to transmit the heat from the heater to the blister package in the particular pattern necessary to seal the blister. When a different shaped blister package needs to be sealed, the heat sealing member is disconnected from the heater and a differently shaped heat sealing member is connected in its place.
A presently known system for changing heat sealing members includes manually operated clamping mechanisms that are normally of the “sheet metal” variety. A conventional clamping configuration is shown in FIGS. 4A and 4B, where a heating member 220 has a sheet metal member 600 positioned against the heater. The heater 220 has a receiving opening 320 and the sheet metal member 600 has an opening 610 adjacent to the receiving opening 320. The opening 610 has a narrow portion 615 and a wider circular portion 620. A heat sealing member 4 has a heat sealing plate 335 and a pole 700. The pole 700 extends from the heat sealing member 4 and has a narrow portion 720 between two wide portions 710, 730. During clamping, the user manually positions the heat sealing member 4 against the heater 220 so that the pole 700 extends through the receiving opening 320 and the wide portion 620 of the opening. To close the clamp, the sheet metal piece 600 is slid in the direction X, and the narrow portion 615 of the opening 610 is positioned around the narrow portion of the pole 720, thereby securing the heat sealing member against the heater 220.
One challenge associated with removably attached heat sealing members involves the clamping of the heat sealing member 4 to the heater 220. During clamping, the user lifts the heat sealing member 4 (which typically weighs about at least 20 lbs.) to a position below the heater 220. The user then lifts the heat sealing member 4 toward the heater 220 so that the poles 700 extend through the openings 320 in the heater 220 and through the openings 610 in the sheet metal clamping apparatus located adjacent to the heater 220. The user then manually slides the sheet metal clamp 600 in the direction X, positioning the narrow portion 720 of the pole 700 in the narrow portion of the opening 610, thereby securing the pole 700 and the heat sealing plate 335 against the heater 220. This operation is generally relatively challenging for the user.
Another issue associated with the conventional method of using heat sealing members involves unclamping and removing the heat sealing member after use. After use, the heat sealing member 4 is very hot for a significant period of time. Should the user not be able to wait for the heat sealing member 4 to adequately cool, the user is often presented with the task of unclamping the heat sealing member 4 while it is still extremely hot. To do this, the user normally wears thermally insulated protective gloves, and holds the heat sealing member 4 with one arm while releasing the clamps with the other arm. The user than removes the heat sealing member 4 from the heat sealing apparatus.
A further challenge associated with the conventional clamping mechanisms of the “sheet metal” variety is their tendency to deform over time, thereby allowing for a gap to be present between the heat sealing member 4 and the heater 220 which can create inefficient heat transfer between the heater 220 and the heat sealing member 4.